TBH it's a really hard question and there's not really a "right" answer. Localization is very subjective; in the context of Yunaka specifically, I am fairly convinced that the person who worked on her genuinely thought that this was a good idea, and in a sense, they're correct: it does sound bizarre and kind of cringy in Japanese as well. Part of the problem is that unusual speech patterns are accepted characterization in Japanese media, whereas they most certainly are not in English media (outside of very specific examples like Yoda), so anytime you have to try and cope with a character who uses one - especially in a case like Yunaka's where her weird speech pattern is part of the persona she uses to cover her real personality, which does not use a weird speech pattern - it's an uphill battle to start with.
You end up in this situation where trying to convey her weird speech pattern, which they genuinely attempted, has a magnified effect because of the cultural differences, resulting in backlash.
Localization, especially for video games which are under far more scrutiny than books/television/music, is this four-way struggle between faithfulness to the text, conveying meaning to a different audience, sounding good in the new language, and being able to be released at all. FF6 famously has Kefka, who was pretty much rewritten from the ground up for the NTSC localization - in the original he was just thoroughly unpleasant and foul-mouthed; Woolsey added basically all of the charming dialogue he's adored for today, and that personality has actually been reverse-adopted into later Japanese works that feature Kefka, such as Dissidia.
That last part - being able to be released at all - is pretty important and I actually don't begrudge the localizers for rewriting the Anna and Jean supports specifically, because in this day and age there was absolutely no way the game would get released in America (their biggest foreign market) with a straight up romance with a little kid. (Alear and half the cast being under 18 doesn't matter, this is an issue of visual perception rather than actual age since, after all, they're just pixels.) To their credit, the rewritten support also leans into Anna's character rather than being simply thrown-together. As a purist, it irritates me, but I'd rather have the game released than not at all. GameBanana and LoversLab, on the other hand, are being ultra-hypocritical about it.
To circle back to the original question, I'd have to change two things. The first is a global thing: as a general rule, the localization tried really hard to play down class distinction and social stratification, because American audiences are perceived as hating nobility and especially imperialism. (I believe that this was part of the decision to assassinate Edelgard's character in the 3H localization, by making her a raging bitch instead of politely venomous and exaggerating her imperialist behavior. Three Hopes, which was translated by a different studio, actually got accused of being "Edelgard Apologist" because the localization was more faithful to the JP.) This is a fairly big problem in a medieval fantasy game, especially when your retinue consists of literal nobility and their retainers and the protagonist has been the center of religious worship throughout the land for the last 1000 years. Similarly, Alear's three retainers have spent not only their lives, but thirty-three generations of family and kin training and preparing for her to awaken, which is why they're so insistent that she butt out of them doing their (her) chores: they literally don't have any reason to be around if she starts doing that.
As an aside, I've seen plenty of people complaining like "oh it's so cringy that Alear introduces herself as the Divine Dragon" or "oh everybody worships you it's so cringe" like. Alear has literally, not figuratively, been set up as this Christ-like figure of worship for 1000 years, of course people are going to worship her. (Alear personally is kind of put out by it, but since she's traveling around in her capacity as the Divine Dragon - undertaking the pilgrimage to the Emblem Rings - of course she's going to introduce herself to people like that, because that's the pertinent information.)
So, to start with, I'd begin by undoing that change and letting the social stratification creep back in. This is important for a few characters on the characterization front to begin with, so it would help there, but for Yunaka specifically, because of her overblown and too-friendly speech style, it allows her to be translated with more straight-up dialogue that is nonetheless noticeably unusual. Think "What's up" rather than "hiya papaya". (Do papayas even exist? Then again, since you can get grapes from fruit trees, it would be fair to suggest that what the game calls a grape might not be what we call grapes IRL.)
A good example of a game that takes this tack is niche but very good Square Enix SRPG "The Last Remnant": in Japanese, the super-friendly but literally-raised-in-isolation-and-never-knew-anyone-but-his-family protagonist Rush meets the local Marquis, Lord David, and doesn't refer to him with an honorific (because Rush only knows his family, who he doesn't use honorifics with that aren't part of the proper noun to begin with). The localization handles this by having Rush shorten "David" to the infinitely more casual "Dave", which conveys the meaning flawlessly to an English ear without sounding really bizarre.
tl;dr localization hard, and never attribute to malice what can be adequately explained by stupidity (alt: the road to hell is paved with good intentions)